An introduction to Azure Functions

In this article

Azure Functions is a solution for easily running small pieces of code, or "functions," in the cloud. You can write just the code you need for the problem at hand, without worrying about a whole application or the infrastructure to run it. Functions can make development even more productive, and you can use your development language of choice, such as C#, F#, Node.js, Java, or PHP. Pay only for the time your code runs and trust Azure to scale as needed. Azure Functions lets you develop serverless applications on Microsoft Azure.

This topic provides a high-level overview of Azure Functions. If you want to jump right in and get started with Functions, start with Create your first Azure Function. If you are looking for more technical information about Functions, see the developer reference.

Features

Here are some key features of Functions:

Choice of language - Write functions using your choice of C#, F#, or Javascript. See Supported languages for other options.

Pay-per-use pricing model - Pay only for the time spent running your code. See the Consumption hosting plan option in the pricing section.

Bring your own dependencies - Functions supports NuGet and NPM, so you can use your favorite libraries.

What can I do with Functions?

Functions is a great solution for processing data, integrating systems, working with the internet-of-things (IoT), and building simple APIs and microservices. Consider Functions for tasks like image or order processing, file maintenance, or for any tasks that you want to run on a schedule.

Functions provides templates to get you started with key scenarios, including the following:

EventGridTrigger - Respond to events delivered to a subscription in Azure Event Grid. Supports a subscription-based model for receiving events, which includes filtering. A good solution for building event-based architectures. For an example, see Automate resizing uploaded images using Event Grid.

ServiceBusQueueTrigger - Connect your code to other Azure services or on-premises services by listening to message queues. For more information, see Service Bus bindings.

ServiceBusTopicTrigger - Connect your code to other Azure services or on-premises services by subscribing to topics. For more information, see Service Bus bindings.

Azure Functions supports triggers, which are ways to start execution of your code, and bindings, which are ways to simplify coding for input and output data. For a detailed description of the triggers and bindings that Azure Functions provides, see Azure Functions triggers and bindings developer reference.

Integrations

Azure Functions integrates with various Azure and 3rd-party services. These services can trigger your function and start execution, or they can serve as input and output for your code. The following service integrations are supported by Azure Functions:

Azure Cosmos DB

Azure Event Hubs

Azure Event Grid

Azure Notification Hubs

Azure Service Bus (queues and topics)

Azure Storage (blob, queues, and tables)

On-premises (using Service Bus)

Twilio (SMS messages)

How much does Functions cost?

Azure Functions has two kinds of pricing plans. Choose the one that best fits your needs:

Consumption plan - When your function runs, Azure provides all of the necessary computational resources. You don't have to worry about resource management, and you only pay for the time that your code runs.

App Service plan - Run your functions just like your web apps. When you are already using App Service for your other applications, you can run your functions on the same plan at no additional cost.